Climate change poses huge challenges and some projections say it will cause hundreds of millions to become refugees. Desertification in sub-Saharan Africa plays a big part of that, and that in turn feeds into Europe's unfolding migrant crisis. Inna Modja is a Malian singer and activist who has been to Senegal for Newsnight to witness a pan-African initiative, the Great Green Wall. It aims to improve livelihoods in the Sahel region, reverse desertification, and break the cycle of exodus.

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